Despite the increased prevalence of asthma in the United States and worldwide, the relationship between asthma and the risk of developing invasive pneumococcal disease is not known. Current guidelines do not recommend routine pneumococcal vaccination for asthmatic patients, although whether they are at an increased risk of morbidity and mortality from invasive pneumococcal disease is unknown. In addition, to what extent asthmatic patients contribute to the burden of invasive pneumococcal disease at a population-level in the post-heptavalent pneumococcal conjugate vaccine era is not known. Availability of effective vaccines is likely to reduce the incidence of invasive pneumococcal disease to a greater extent if subgroups of high-risk patients who can be targeted for vaccination are identified. The proposed study is an indispensable step toward formulating a rational pneumococcal vaccine policy for asthmatic children and adults. If an association between asthma and invasive pneumococcal disease is found, it will lead to further research into the mechanisms of such an association as well as studies of the possible relationship between asthma and other microbial infections. Furthermore, recent studies suggest those bacteria and their products positively (e.g., super antigens) or negatively (e.g., hygiene hypothesis) affect the development of asthma. However, our knowledge is severely lacking about how asthma or other allergic conditions influence the susceptibility to microbial infections. Therefore, our study findings may influence the current paradigm for understanding the causal relationship between microbial infections and asthma. The goal of this study is to determine the relationship between asthma and invasive pneumococcal disease. The study will accomplish this goal by conducting a population-based case-control study composed of an estimated 373 invasive pneumococcal disease cases and 1:2 dates of birth- and gender-matched controls (746) among the residents of Rochester, Minnesota, between 1964 and 1983. The specific study aims developed from our preliminary work are: 1. To determine the susceptibility of asthmatic patients to invasive pneumococcal disease by testing the hypothesis that the frequency of asthma is higher among patients with invasive pneumococcal disease than among matched controls. 2. To determine the severity of invasive pneumococcal disease among asthmatic patients by testing the hypothesis that among persons with invasive pneumococcal disease, asthmatic patients have longer duration of hospitalization for invasive pneumococcal disease than patients without asthma. Our study site is ideal for the proposed study for the following reasons: (1) we have previously identified all 2499 incident cases of asthma among children and adults in Rochester, Minnesota between 1964 and 1983; (2) the number of cases of invasive pneumococcal disease during this time period will provide sufficient power to accomplish our specific aims; and (3) the study will be performed during the pre-pneumococcal vaccine era so that confounding by vaccine status will not occur.